Liquid metal micro switches (LIMMS) have been made that use a liquid metal, such as mercury, gallium-bearing alloys or other liquid metal compositions, as the switching fluid. The liquid metal may make, break or latch electrical contacts. To change the state of the switch, a force is applied to the switching fluid, which causes it to change form and move. Liquid metal switches rely on the cleanness of the liquid metal for good performance. If the liquid metal forms oxide films or other types of corrosion product buildup within the switch, the proper functioning or performance of the switch may degrade or be inhibited.
For example, the oxide film or other corrosion products may increase the surface tension of the liquid metal, which may increase the energy required for the switch to change state. Films of oxide and other corrosion products may increase the tendency for the liquid metal to wet to the substrate between switch contacts, thereby increasing undesirable short circuits in the switching operation. Build up of oxide and other corrosion products may also degrade the ability of the liquid metal to wet to the switch contacts, and thereby may increase the probability of undesirable open circuits in the switching operation. The build up of oxide and other corrosion products within the liquid metal switch may also alter the effective surface tension of the liquid metal with itself, causing the liquid metal to become stringy when moved or stretched, and thereby decreasing the tendency of the liquid metal to break cleanly between switch contacts and potentially causing short circuits. Build up of large amounts of oxide or corrosion products may increase the effective viscosity of the liquid metal leading to slower switch operation over time.
It is desirable to have liquid metal that is as free of oxide and other corrosion products as practically possible in order to minimize the above mentioned negative effects. There is a need for a method to decrease or eliminate the build up of oxide or other corrosion products in liquid metal switches.
In one embodiment, a method for reducing oxides and corrosion products on a switching fluid is disclosed. The method includes depositing a switching fluid on a first substrate. The first substrate is mated to a second substrate, the first substrate and the second substrate defining therebetween a cavity holding the switching fluid. The cavity is sized to allow movement of the switching fluid between first and second states. The switching fluid is coated with a corrosion inhibitor.